I managed to update without issues using the following process on a Windows 11 laptop and MG4 XPower:
1)
https://iov-mapmg.soimt.com
2) Enter VIN only (no need for fingerprint)
3) Click on map link to download (it's a ~17GB so it takes a while)
4) Formatted 32GB USB key to exFAT
5) Extracted "Maps" folder to the same folder on the USB Key (this took several hours)
6) Connected USB key to car and navigated to the map update section (system menu)
7) Followed instructions and waited for "OK" button to be selectable then waited
The car did an MD5 check first then copied then another check which makes sense - that took about 25 minutes as others have said. It then asked to reboot and I now have the latest maps.